Desperately searching for engine rebuild / overhauling topics

[Figoulu]

Hi gents,

As the title says, i’m looking for such subjects to help my decision process...
In fact my car needs engine restoration and i’d like to know wether i can do it by myself or not

I got the shop manual, technical reviews, and rebuilt already a porsche 911 engine... few years ago
This being said i welcome your leads on this forum by means of copy/paste of links to correct topics or any other valuable informations

Thanks by advance

[MikeSimon]

I think it very much depends on what your engine really needs. If you divide it into two segments - short block and cylinder head - you may get a much better idea of what is needed, what you can do yourself and what you have to pay big money for. For some stuff, a regular shop working on engines of all kinds may be able to help at a lower cost, for others you need a place that is experienced in the Mercedes stuff. Of course the Fuel Injection pump is an item all by itself.

[Dave H]

The following Engine rebuild guide should keep you right .
Good luck

[mdsalemi]

The following Engine rebuild guide should keep you right .
Good luck

Don't know what that is, Dave H, but its 0kb and empty. Nothing there.

[Figoulu]

I think it very much depends on what your engine really needs. If you divide it into two segments - short block and cylinder head - you may get a much better idea of what is needed, what you can do yourself and what you have to pay big money for. For some stuff, a regular shop working on engines of all kinds may be able to help at a lower cost, for others you need a place that is experienced in the Mercedes stuff. Of course the Fuel Injection pump is an item all by itself.

You’re right i should have been more precise about the situation

Well... i bought the car as non functional because the cylinders are scratched according to the mechanic where the car was. The engine wasn’t seized and i could check it before buying it, by simply using the starter.
Deal was done, car brang to my garage...

After cleaning the 7 injectors and after 2/3 checkings the engine started up, enough to bring it to the local MOT, a must to end up the paper works and make this pagoda definitely mine. But the idle is catastrophic, and clearly impossible to have a correct powerful output. Heavy smell of unburned gasoline...

Now... i checked the inside of the cylinders and took the compressions. Those are not so catastrophic, while scratches inside cylinders are sometimes awful, sometimes acceptable depending which cylinder is inspected. I used a small endoscopic camera.
I removed the FPI and prepare to send it to a pro.

Next step is the engine, and my wonderings...

Everything is on my youtube channel for those who can understand french : https://youtu.be/2W-a0HYLUSI

Hope you can help with links or advices

[Figoulu]

The following Engine rebuild guide should keep you right .
Good luck

Empty link, but very promising title 👍👍👍👍

[Cees Klumper]

Watched the video, some thoughts:
- did you adjust ignition timing?
- since you tested compression with fuel pump going, I would put in a fresh set of spark plugs
- the two nuts fixing the 'post' on the driver's side of the engine, that holds up the injection linkages transverse control rod, are on backwards; the chamfered side should be towards the bracket
- did you test to see whether the cold start valve is leaking?
- possibly the idle mixture setting on the pump is way too rich. Try turning it out a click or two, and/or adding air with the slotted screw on the intake manifold

Good luck with the project, looks like a nice car.

[kampala]

Also watched your videos.  Compression is strong almost surprisingly strong on #6. 

Since you are a full member you should throughly do the “linkage tour” after checking the items Cees mentioned. 

It it were me, I would not remove the injection pump until I confirmed the linkage and all starting aids are working and not adding fuel at wrong times. 

Bon Courage

[Figoulu]

Watched the video, some thoughts:
- did you adjust ignition timing?
- since you tested compression with fuel pump going, I would put in a fresh set of spark plugs
- the two nuts fixing the 'post' on the driver's side of the engine, that holds up the injection linkages transverse control rod, are on backwards; the chamfered side should be towards the bracket
- did you test to see whether the cold start valve is leaking?
- possibly the idle mixture setting on the pump is way too rich. Try turning it out a click or two, and/or adding air with the slotted screw on the intake manifold

Good luck with the project, looks like a nice car.

To answer properly:

I did not tune anything related to ignition timing, since I checked there was a spark on each cylinder, that was enough for the moment. I guess I'll need to buy a stroboscopic light...
The mechanic where the car was standing for months / years has been instructed and paid by the previous owner to make it start prior to selling it. What he did for couple of thousand euros was to check / change the ignition system: cover, wires, condensator and breakers, battery, spark plugs and several other things (4 tires, break lines and cylinders, and all the fluids...). He could then restat the car but after a while it definitely stalled. His conclusion was that the engine was so worn, that the compressions couldn't reach a minimum level to make it run. My understanding now, is that the car was running so rich that it has been washing the inside of the cylinders, removing the oil layer, enough to damage the cylinders with the piston rings. He sent an endoscopic camera to show the wear and made the conclusion himself. But I guess it was also so rich that the engine couldn't start anymore.

Ignition appears "clean" and don't suspect there could be an issue, but I admit it needs double checking / tuning for sure... but what I couldn't really figure out for now is the firing order and its weird connection over the head of the distribution. I suspect there could be some mistakes maybe causing misfirings.

Spark plugs: Ok to change them but they are like new (old are in the trunk) except that black soot that made me immediately think about an issue with FIP / Injectors. Once 7 injectors cleaned by US the engine fired up. Then I decided to remove the FIP after the MOT has been completed, and make it restored. Its on its way now. For sure the mechanic didn't touch the FPI because the poor remaining quantity of oil was dark as a coke...

So considering the darkness of the injector + the spark plugs, I adressed all the injection system before I go for more.

But the comment you made on my video let me understand that you feel positive. Do you think I can live with such cylinders ? Could you tell me more ?
Thanks again

[Figoulu]

Also watched your videos.  Compression is strong almost surprisingly strong on #6. 

Since you are a full member you should throughly do the “linkage tour” after checking the items Cees mentioned. 

It it were me, I would not remove the injection pump until I confirmed the linkage and all starting aids are working and not adding fuel at wrong times. 

Bon Courage

Thanks. I will for sure

Compression is quiet tricky and numbers are surprising... I guess that the precision of the measure is not like a swiss watch....
My intention was to check wether I could detect a major failure or something that says 1 or 2 cylinders are toasted. But apparently not...
Pump is already out of the car, and all the linkage removed to be soon zinc plated. I will double check when I get everything back in the car

I guess there also could be an issue with the rocker arms. I bought a special tool to tune them up. I could already see that it has to be...

[Cees Klumper]

Yes, I would do all the basics on the engine: ignition timing, spark plug wire resistance, idle air/fuel mixture, fuel pressure and flow rate (also when the engine is warm, the pump could be tired or dirt in the tank), valve clearances. Not necessary to do all at once, just one step at a time. Also check the timing chain and general timing of the camshaft vis-a-vis the pistons and crankshaft. Basically every aspect of the engine. Since you have no real idea about what was done, and how competently, before you bought the car, it's worthwhile to check everything. Low compression in some cylinders could be due to a stuck piston ring that might work itself loose (although I am not sure about that one). Only as a last resort remove and rebuild the engine if really necessary.
If it has enough compression to start and run for a while, it has enough to keep running, I would think.

[Harry]

I just finished rebuilding my 1966 230SL engine (block and head) and it is an expensive undertaking.  I would probably not recommend touching the block with your compression numbers - they still look strong (those that I saw).  When it runs, how is oil pressure?  That's  another key indicator of health.  I agree with Cees to start working through other things.  The engine sounded a bit noisy to me and I wonder whether the timing chain is tight enough.  Check valve clearances also.

[Figoulu]

Yes, I would do all the basics on the engine: ignition timing, spark plug wire resistance, idle air/fuel mixture, fuel pressure and flow rate (also when the engine is warm, the pump could be tired or dirt in the tank), valve clearances. Not necessary to do all at once, just one step at a time. Also check the timing chain and general timing of the camshaft vis-a-vis the pistons and crankshaft. Basically every aspect of the engine. Since you have no real idea about what was done, and how competently, before you bought the car, it's worthwhile to check everything. Low compression in some cylinders could be due to a stuck piston ring that might work itself loose (although I am not sure about that one). Only as a last resort remove and rebuild the engine if really necessary.
If it has enough compression to start and run for a while, it has enough to keep running, I would think.

Hi Cees,

Thanks for your advices. I will carry on as my fip is back.
I’ll keep everybody posted 👍👍👍

[Figoulu]

I just finished rebuilding my 1966 230SL engine (block and head) and it is an expensive undertaking.  I would probably not recommend touching the block with your compression numbers - they still look strong (those that I saw).  When it runs, how is oil pressure?  That's  another key indicator of health.  I agree with Cees to start working through other things.  The engine sounded a bit noisy to me and I wonder whether the timing chain is tight enough.  Check valve clearances also.

Understood.
Thanks again 👍👍👍

[Figoulu]

By the way guys as a newbie, i really appreciate your advices, and the way you comfort me to use the correct path

[Shvegel]

I used to teach diagnostics for BMW and when I did that I gave a talk on the seven mistakes you can make as a diagnostician.  One of them was "Trust someone else."  It is very common when someone hands you something they can't fix to list everything they did, "I checked this and this and this."  I told my students to smile, nod you head and then start over.  Most of the times this occurs because they missed something.  You need to know for you.

Here is what I would do. replace the points and condenser.  The car really sounds like the points are burned. Personally I would buy a Pertronix Ignitor conversion and eliminate the points all together.  Message me if you do use the Pertronix as there is a small detail left out of the instructions that causes problems.  Verify that the "New" (new means Never Ever Worked) Spark plug wires have a metal center conductor and are not carbon / glassfibre cores.  If they are glassfibre cored they almost certainly have too much resistance and will effect spark.  You need to make sure the spark is getting to the cylinders reliably and at the right time.  Also check to see if the "new" spark plugs have an R in the part number?  Again added resistance.  Remember, if the fuel isn't burning it is going to appear rich.  Many rich running engines are due to ignition problems.

After checking the ignition the two things I would check on the fuel system are the rack in the injector pump being free and the cold start injector not leaking.  With the pump off as you have it now remove the steel side cover with the 6 screws on it.  At the top of that opening you will see a line of little black clamps with screws on them. you should be able to move those clamps side to side and they should return to their original position.  If that works you are most of the way there.  The injection pumps are very robust and do not slip out of adjustment easily so although you may have hot start or cold start issues but when it is running it should be OK.

As for the cold start when you have it back together remove the tiny hex head bolt on the side of the cold start injector. start the car and see if fuel leaks out?  If it does you cold start injector is leaking.

Everything I hear and see says ignition issue.   I think most likely it is burned points as it ran and gradually faded out on the mechanic. 

[Figoulu]

I was planning to replace the ignition system by an electronic one.
Do you recommand PerTronix ? And Which ref ?

Thanks

[Shvegel]

Be prepared for an avalanche of suggestions.  Personally I like the Pertronix.  It is simple, reliable and easily hidden.  Read the directions and make sure you have the proper resistor in line etc.  If you do go with pertronix you need to grind the ignition rotor bottom down a little so the rotor doesn't sit too high and damage the distributor cap.  If it is a bosch rotor I grind until I hit the step in the plastic. 5mm or so.

Pretty sure it is a Pertronix 1863.  Compare the plate without the module with your points.  recessed hole in plate is for the screw that retains your points.

https://www.ebay.com/itm/114803481088?epid=203190728&hash=item1abad21a00:g:9soAAOSwwnBgmvSz

I grind off the part hanging down where the shaft goes in.

https://www.pelicanparts.com/More_Info/0001582031.htm?pn=000-158-20-31-M14

[Figoulu]

Thanks.
I spotted this one as well... as you mentioned, making the right choice is the most challenging thing...

https://www.summitracing.com/parts/fst-3000-0231

[Shvegel]

I had a Pertronix in my car for years and it never skipped a beat.  I took it off during the restoration and spent $$$ recreating the original electronic ignition for my 1970 US spec car.  I gave the Pertronix to JohnK when he had similar issues to yours and it is still chugging along.

[Figoulu]

I had a Pertronix in my car for years and it never skipped a beat.  I took it off during the restoration and spent $$$ recreating the original electronic ignition for my 1970 US spec car.  I gave the Pertronix to JohnK when he had similar issues to yours and it is still chugging along.

👍👍👍

[Cees Klumper]

Also have a look at the 123 ignition. Fully electronic and you get a brand new distributor, which will eliminate any issues caused by the old distributor being worn out (bushings, centrifugal mechanism, advance canister etc). I have it on my Pagoda, Datsun 240Z and Lancia Fulvia.

[Figoulu]

Thanks 👍👍👍